U.S. patent application number 09/734138 was filed with the patent office on 2002-08-22 for polymer stabilization.
Invention is credited to Amick, David Richard, Harris, Jerome Michael, Mattox, John Robert.
Application Number | 20020115765 09/734138 |
Document ID | / |
Family ID | 26868637 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020115765 |
Kind Code |
A1 |
Amick, David Richard ; et
al. |
August 22, 2002 |
Polymer stabilization
Abstract
Disclosed are stable polyurethane thickener compositions and
methods for stabilizing such compositions. Stabilized microbicide
compositions and methods for stabilizing such microbicides are
disclosed. Also disclosed are stable polyurethane thickener
compositions containing microbicides.
Inventors: |
Amick, David Richard;
(Doylestown, PA) ; Harris, Jerome Michael;
(Penllyn, PA) ; Mattox, John Robert; (Perkasie,
PA) |
Correspondence
Address: |
Wendy A. Choi
Rohm and Haas Company
100 Independence Mall West
Philadelphia
PA
19106-2399
US
|
Family ID: |
26868637 |
Appl. No.: |
09/734138 |
Filed: |
December 11, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60172947 |
Dec 21, 1999 |
|
|
|
Current U.S.
Class: |
524/244 ;
523/122 |
Current CPC
Class: |
C08K 5/0058 20130101;
C08K 5/0058 20130101; C08L 83/04 20130101; A01N 2300/00 20130101;
A01N 43/80 20130101; C08G 2130/00 20130101; A01N 43/80
20130101 |
Class at
Publication: |
524/244 ;
523/122 |
International
Class: |
C08K 003/00 |
Claims
What is claimed is:
1. A composition comprising one or more water grade polyurethane
thickeners, water, a stabilizer comprising diethyl hydroxyl amine
or 4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl, and optionally one
or more 3-isothiazolone microbicides, wherein the composition is
substantially free of organic solvent.
2. The composition of claim 1 wherein the stabilizer is present in
an amount of 1 to about 5000 ppm.
3. The composition of claim 2 wherein the stabilizer is present in
an amount of 10 to about 500 ppm.
4. The composition of claim 1 wherein the 3-isothiazolone is a
mixture of 5-chloro-2-methyl-3-isothiazolone and
2-methyl-3-isothiazolone.
5. A latex composition comprising the stabilized composition of
claim 1.
6. A method for stabilizing thickening agent compositions
comprising one or more polyurethane thickening agents comprising
the step of contacting the composition with a stabilizer comprising
diethyl hydroxyl amine or
4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl, wherein the thickening
agent optionally comprises one ore more 3-isothiazolone
microbicides and wherein the composition is substantially free of
organic solvent.
7. The method of claim 6 wherein the diethyl hydroxyl amine or
4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl is present in an amount
of 1 to about 5000 ppm.
8. The method of claim 6 wherein the 3-isothiazolone is a mixture
of 5-chloro-2-methyl-3-isothiazolone and
2-methyl-3-isothiazolone.
9. A stable microbicide composition comprising one or more
3-isothiazolone compounds and a stabilizer comprising diethyl
hydroxyl amine or 4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl.
10. The microbicidal composition of claim 9 further comprising
water.
11. The stable microbicide composition of claim 9 wherein the
3-isothiazolone compound is selected from
5-chloro-2-methyl-3-isothiazolo- ne, 2-methyl-3-isothiazolone,
2-n-octyl-2-isothiazolone, 4,5-dichloro-2-n-octyl-3-isothiazolone,
benzisothiazolone, 2-methyl-4,5-trimethylene-3-isothiazolone, and
mixtures thereof.
12. A method for stabilizing a microbicide comprising the step of
contacting one or more 3-isothiazolone compounds with a stabilizer
comprising diethyl hydroxyl amine or
4-hydroxy-2,2-6,6-tetramethylpiperid- inoxyl.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to the stabilization of
certain polymers. In particular, this invention relates to the
stabilization of certain water-based urethane polymers.
[0002] Latticies and other aqueous systems can require thickening,
that is their viscosity must be increased, for certain processing
conditions and certain end uses. Such thickeners often impart or
improve other properties as well. For example, thickeners are used
in latex paints not only for viscosity improvement and control, but
also for protective colloidal action and for improvement of pigment
suspension, leveling and flow. In addition, the thickeners often
emulsify, disperse and stabilize latex ingredients and are
themselves film formers. Such thickening additives can also improve
the sticking of binding properties of the composition.
[0003] Typically, thickening agents are commercially available as
either "solvent grade" or "water grade." Solvent grade thickeners
refer to those thickeners dissolved or dispersed in a mixture of
water and organic solvent. Water grade thickeners refer to those
thickeners that are dissolved or dispersed in water.
[0004] One well-known class of such thickening agents are the low
molecular weight polyurethanes. Such polyurethane thickeners are
typically nonionic. For example, U.S. Pat. No. 4,079,028 (Emmons)
discloses non-ionic polyurethanes having at least three low
molecular weight hydrophobic groups at least two of which are
terminal (external) hydrophobic groups.
[0005] Many commercially available thickeners, such as polyurethane
thickeners, contain ethylene oxide chains. Under certain processing
conditions, these commercial thickeners, both solvent and water
grades, suffer from degradation of the ethylene oxide chain. Once
such degradation occurs, the thickener loses some or all of its
viscosity improving ability. Certain stabilizers, such as butyrated
hydroxytoluene ("BHT") have been added to stabilize solvent grade
thickeners. For example, the Encyclopedia of Polymer Science and
Engineering, vol. 6, John Wiley & Sons, New York, page 252
(1986), discloses that poly(ethylene oxide) compounds can be
stabilized against degradation through the use of 0.01 to 0.5
percent by weight phenothiazine, BHT, or butyrated hydroxyanisole
("BHA"). Such stabilizers are not effective at stabilizing water
grade polyurethane thickeners.
[0006] Commercially available thickeners, particularly water grade
thickeners, also suffer from microbial attack. Microbicides have
been used to preserve water grade thickeners against microbial
attack. One class of microbicides that is particularly suited to
the stabilization of thickeners is 3-isothiazolones, and in
particular a 3:1 mixture of 5-chloro-2-methyl-3-isothiazolone and
2-methyl-3-isothiazolone.
[0007] While 3-isothiazolones are very effective microbicides, they
suffer from being unstable under certain conditions, particularly
in the presence of nucleophiles. Without the presence of a
stabilizer, many 3-isothiazolones chemically degrade and lose
microbicidal efficacy. For example, U.S. Pat. No. 5,599,827
(Gironda) discloses the stabilization of
5-chloro-2-methyl-3-isothiazolone and/or 2-methyl-3-isothiazolone
by forming a microemulsion with organic solvents having less than 6
percent by weight solubility in water and anionic surfactants.
However, such stabilized isothiazolones are costly to use and
introduce other components, such as different or unwanted
surfactants, into the polyurethane thickener composition.
[0008] U.S. Pat. No. 4,920,137 (Segall) discloses various
substituted phenyl compounds as stabilizers for 3-isothiazolones.
However, such stabilizers are not very effective in stabilizing
3-isothiazones in aqueous compositions. Also, undesired precipitate
may occur in aqueous 3-isothiazolone compositions stabilized with
these substituted phenyl compounds.
[0009] Thus, there is a continuing need to stabilize water grade
polyurethane thickeners, to stabilize 3-isothiazolone compounds,
and particularly to stabilize both polyurethane thickeners and
3-isothiazolone compounds in combination.
SUMMARY OF THE INVENTION
[0010] The inventors have surprisingly found that diethyl hydroxyl
amine and 4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl reduces the
degradation of water grade polyurethane thickeners. It has been
further surprisingly found that diethyl hydroxyl amine and
4-hydroxy-2,2-6,6-tetramethylpiperi- dinoxyl stabilize the
3-isothiazolone microbicides used in such water grade polyurethane
thickeners.
[0011] In one aspect, the present invention provides a composition
including one or more water grade polyurethane thickeners, water, a
stabilizer including diethyl hydroxyl amine or
4-hydroxy-2,2-6,6-tetramet- hylpiperidinoxyl, and optionally one or
more 3-isothiazolone microbicides, wherein the composition is
substantially free of organic solvent.
[0012] In a second aspect, the present invention provides a method
for stabilizing thickening agent compositions including one or more
polyurethane thickening agents including the step of contacting the
composition with a stabilizer including diethyl hydroxyl amine or
4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl, wherein the composition
optionally includes one ore more 3-isothiazolone microbicides and
wherein the composition is substantially free of organic
solvent.
[0013] In a third aspect, the present invention provides a latex
composition including the stabilized polyurethane thickener
composition described above.
[0014] In a fourth aspect, the present invention provides a stable
microbicide composition including one or more 3-isothiazolone
compounds and a stabilizer including diethyl hydroxyl amine or
4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl.
[0015] In a fifth aspect, the present invention provides a method
for stabilizing a microbicide including the step of contacting one
or more 3-isothiazolone compounds with a stabilizer including
diethyl hydroxyl amine or
4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl.
DETAILED DESCRIPTION OF THE INVENTION
[0016] As used throughout this specification, the following
abbreviations shall have the following meanings, unless the context
clearly indicates otherwise: g=gram; .degree. C.=degrees
Centigrade; mL=milliliter; wt %=weight percent; ppm=parts per
million; and DI=deionized.
[0017] The terms "thickener" and "thickening agent" are used
interchangeably throughout this specification. As used herein, the
term "polymer" refers to the water grade polyurethanes of the
present invention. The term "microbicide" refers to a compound
capable of inhibiting the growth of or controlling the growth of
microorganisms at a locus. The term "microorganism" includes, but
is not limited to, bacteria, fungi and algae. "Preservative" and
"microbicide" are used interchangeably throughout this
specification.
[0018] As used throughout this specification, the term "hydrophobe"
includes not only the hydrocarbon residues of hydroxyl, amino or
isocyanate reactants, but also the combination of such residues
with the next adjacent urethane and other groups remaining in the
structure after reaction. The term "hydrophobe" refers to all those
portions or segments of the polymeric reaction products which
contribute to water insolubility. All portions or segments other
than the residues of the polyether polyol reactants therefore are
hydrophobic.
[0019] All amounts are percent by weight and all ratios are by
weight, unless otherwise noted. All numerical ranges are
inclusive.
[0020] The stable water grade thickener compositions of the present
invention include one or more polyurethane thickeners, water and a
stabilizer including diethyl hydroxyl amine or
4-hydroxy-2,2-6,6-tetramet- hylpiperidinoxyl, wherein the
composition is substantially free of organic solvent. By
"substantially free" of organic solvent is meant that the
composition contains about 5 percent or less by weight organic
solvent, based on the total weight of the composition. It is
preferred that the water grade thickeners of the present invention
are essentially free of organic solvent, that is, that the
compositions contain about 2 percent or less by weight organic
solvent, based on the total weight of the composition. It is
further preferred that the water grade thickeners of the present
invention are free of organic solvent.
[0021] Any polyurethane thickener that is water soluble or can be
dispersed in water is suitable for use in the present invention.
Suitable polyurethanes for use in the present invention include,
but are not limited to those disclosed in U.S. Pat. Nos. 4,079,028;
5,023,309 (Kruse et al.); 4,499,233 (Tetenbaum et al.) and
4,426,485 (Hoy et al.), all of which are herein incorporated by
reference.
[0022] Typically, polyurethane thickeners having more than 30
ethylene oxide ("EO") units and a hydrophobe containing a carbon
chain having less than eight carbons are water soluble.
Polyurethane thickeners having a hydrophobe containing eight
carbons or greater must be "compatibilized" in order to be
dissolved or dispersed in water. Such compatibilization is
typically achieved through the use of a compatibilizer. A
compatibilizer is any compound which prevents or reduces
self-association of the polyurethane thickener when the thickener
is combined with water. Such compatibilizers are known to those
skilled in the art.
[0023] Suitable polyurethane thickeners for use in the present
invention include, but are not limited to, nonionic polyurethanes
having at least three low molecular weight hydrophobic groups at
least two of which are terminal (external) hydrophobic groups. It
will be appreciated by those skilled in the art that the
polyurethanes of the present invention may contain one or more
internal hydrophobic groups. Typically, the hydrophobic groups
together contain a total of at least 20 carbon atoms and are linked
through hydrophylic (water soluble) groups containing polyether
segments of at least about 1500, preferably at least about 3000
molecular weight each so that the polyurethanes readily solubilize
in water or can be dispersed in water, either with or without a
compatibilizer. In general, the molecular weight of the
polyurethanes is about 10,000 to about 200,000.
[0024] Particularly useful polyurethane thickeners are those
disclosed in U.S. Pat. No. 4,079,028, herein incorporated by
reference to the extent it teaches the preparation and use of such
thickeners. Typically, the polyurethane polymers of the present
invention are prepared in non-aqueous media and are the reaction
products of at least reactants (a) and (c) of the following
reactants: (a) at least one water soluble polyether polyol, (b) at
least one water insoluble organic polyisocyanate, (c) at least one
monofunctional hydrophobic organic compound selected from
monofunctional active hydrogen compounds and organic
monoisocyanates, and (d) at least one polyhydric alcohol or
polyhydric alcohol ether. The products formed include the
following:
[0025] 1. Reacton products of a reactant (a) containing at least
three hydroxyl groups, and the foregoing organic
monoisocyanates;
[0026] 2. Reaction products of reactant (a), reactant (b)
containing two isocyanate groups, and the foregoing active hydrogen
containing compounds, such as those wherein the ratio of
equivalents of (a) to (b) is 0.5:1 to 1:1;
[0027] 3. Reaction products of reactant (a), reactant (b)
containing at least three isocyanate groups, and the active
hydrogen containing compounds;
[0028] 4. Reaction products of reactant (a), reactant (b) and the
organic monoisocyanates; and
[0029] 5. Reaction products of reactants (a), (b), (d) and the
organic monoisocyanates.
[0030] By "monofunctional active hydrogen compound" is meant an
organic compound having only one group which is reactive with
isocyanate, such group therefore containing an active hydrogan
atom, any other functional groups, if present, being substantially
unreactive to isocyanate. Such compounds include monohydroxy
compounds such as alcohols, alcohol ethers and monoamines, as well
as polyfunctional compounds providing the compound is only
monofunctional to isocyanates. For example, the primary amines,
although difunctional in many reactions, are only monofunctional
towards isocyanates, the hydrogen atom in the resulting urea group
being relatively unreactive to isocyanate as compared with the
hydrogen atom of the amino group or of unhindered alcohols.
[0031] Reactant (c) is a "capping" compound, meaning it reacts with
("caps") the terminal functional groups of the reaction product of
reactants (a) and (b). The polyether polyol reactant (a) is an
adduct of an alkylene oxide and a polyhydric alcohol or polyhydric
alcohol ether, a hydroxyl-terminated prepolymer of such adduct and
an organic polyisocyanate, or a mixture of such adducts with such
prepolymers.
[0032] Reactant (d) may be employed to terminate isocyanate
functionality or to link isocyanate-terminated reaction
intermediates. Reactant (d) may be a polyhydric alcohol or
polyhydric alcohol ether of the same type as used to form the
adducts of reactant (a). The polyhydric alcohols or alcohol ethers
may be aliphatic, cycloaliphatic or aromatic and may be used singly
or in mixtures of either type or mixtures of the two types.
[0033] The organic polyisocyanates include simple di- and
triisocyanates, isocyanate-terminated adducts of such polyhydric
alcohols and organic di- or triisocyanates, as well as
isocyanate-terminated prepolymers of polyalkylene ether glycols and
organic di- or triisocyanates.
[0034] The hydrophobic groups of the polyurethanes occur in the
residues of reactants (b) and (c) and may also occur in the residue
of reactant (d) if present. The terminal (external) hydrophobes are
the residues of the monofunctional active hydrogen compounds,
organic monoisocyanates, or combinations of the residues of such
compounds.
[0035] Typically, the water grade polymeric thickeners of the
present invention are polyurethanes which may be classified as
linear products (Group A), star-shaped products (Group B) or
complex polymers (Group C).
[0036] Suitable linear products are those of the formula
[0037] A--B.sub.p--E.sub.q--(B--E)m--B.sub.r--E.sub.t--A
[0038] where each of p, q, r and t independently is zero or 1; at
least one of q and r is 1; and t is zero when r is zero; provided
that, when q is 1, then a) each of p, r and t is zero (as in
formula I, below); or b) p is zero and each of r and t is 1 (as in
formula II, below); or c) t is zero and each of r and p is 1 (as in
formula III, below); and when q is zero, then r is 1 and each of p
and t is zero (as in formula IV, below).
[0039] Polymers coming within the foregoing linear products formula
include, but are not limited to:
[0040] I. A--E--(B--E).sub.n--A
[0041] II. A--E--(B--E).sub.n--B--E--A
[0042] III. A--B--E--(B--E).sub.n--B--A
[0043] IV. A--(B--E).sub.n--B--A
[0044] The equivalent ratio of total active hydrogen to total
isocyanate in the Group A compounds is about 1:1 to 2:1.
[0045] Suitable star-shaped products are those of the formula
[0046]
[H--E--OCH.sub.2],.sub.s--L--[Q.sub.v--(D.sub.u--E--A).sub.w--R.sub-
.z].sub.m.
[0047] wherein L is X, Y or --O--; Q is ----CH.sub.2C.ident.; D is
----CH.sub.2O------; m is 2-4; s is zero to 2; m+s is the valence
of L (2-4); w is 1-3, and each of u and z is independently zero or
1; and where X is a hydrocarbon radical containing at least 1
carbon atom, preferably 1-4 carbon atoms; and Y is a trivalent
radical selected from
[0048]
--OCONH(CH.sub.2).sub.6N[CONH(CH.sub.2).sub.6NHC(O)O].sub.2----;
[0049] CH.sub.3C[CH.sub.2O--OCNHC.sub.7H.sub.6NHC)].sub.3----;
and
[0050]
CH.sub.3CH.sub.2C[CH.sub.2O--OCNHC.sub.7H.sub.6NHCO].sub.3----;prov-
ided that, a) when L is X, then u and w are each 1, v and z are
each zero, m+s=4, and m is at least 2 (as in formula V below); b)
when L is Y, then u, v and s are each zero, m is 3, w is 2-3, and z
is zero or 1 (as in formula VI below); and c) when L is--O--, then
v and u are each 1, w is 1-3, m is 2 and each of s and z is zero
(as in formula VII below).
[0051] Polymers within the foregoing formula include, but are not
limited to:
[0052] V. (H--E--OCH.sub.2).sub.s--X--[CH.sub.2O--E--A].sub.m
[0053] VI. Y[(E--A).sub.wR].sub.3
[0054] VII. O[CH.sub.2C{CH.sub.2O--E--A}.sub.3 ].sub.2
[0055] In each of the polymers of Groups A and B: A and R are
hydrophobic organic radicals containing at least one carbon atom; B
is a divalent hydrophobic group of the structure 1
[0056] wherein G is the residue of an organic di- or triisocyanate,
the residue having no remaining unreacted isocyanate groups; E is a
divalent, hydrophillic, nonionic polyether group; and n is at least
1, such as about 1-20, preferably 1-10.
[0057] In structures V and VII, the equivalent ratio of total
active hydrogen to total isocyanate is from about 1.2:1 to a
stoichiometric excess of isocyanate; and in structure VI from about
1:1 to a stoichiometric excess of active hydrogen.
[0058] It will be apparent to the polymer chemist that values of n
given in this specification are average rather than absolute values
since in reaction products of the type of this invention, the
reaction product will often be a mixture of several products having
different values for n.
[0059] The star-shaped polymer configurations of formulas V-VII
result from a polyhydric reactant such as trimethylolpropane or
pentaerythritol (residue X in formula V) or a triisocyanate
(residue Y in formula VI), or result from polyhydroxyether such as
dipentaerythritol (Q and D of formula VII). L, Q and D form a
central hydrophobic nucleus from which radiate hydrophilic
polyether segments E, partially or fully capped (terminated) with
hydrophobic groups A and R. The points or arms may have the same or
different chain length and may contain hydrophobic segments
alternating with hydrophilic portions. When s is greater than zero,
partial capping results. In formulas V and VII, A is the residue of
an organic monoisocyanate.
[0060] The complex polymer form of the polyurethanes of the present
invention are complex mixtures of linear, branched and sub-branched
products which form networks of hydrophobes and hydrophobic
segments interspersed with hydrophilic segments. The products
result from the multitude of different interactions which may take
place between the polyfunctional reactants used to form them. The
essential reactants are a polyfunctional compound containing at
least three hydroxyl or isocyanate groups, a difunctional compound
reactive with the polyfunctional compound, and a monofunctional
reactant such as a monohydroxy or monoamino compound. The reactants
may each be present singly or in mixtures of two or more. The
difunctional compound is a diisocyanate (for reaction with the
triol or higher polyol) or a diol (for reaction with the
triisocyanate) and can also be present singly or in mixtures of two
or more. The monohydroxy or monoamino compound, or mixture thereof,
is added to the reaction mixture to cap isocyanate of the
triisocyanate not reacted with the diol in order to prevent
gelation. A monoisocyanate may be added to the reaction mixture if
some of the polyol (diol, triol or higher polyol) remains unreacted
or if it is desired to cap all hydroxyl groups.
[0061] It should be understood that in preparing the complex
polymers of the present invention (Group C) as well as those of
Groups A and B, capping of all hydroxyl is not required. Capping or
hydrolyzing of all isocyanate, although not absolutely necessary,
is preferred to avoid toxicity in the polymeric product. Generally,
no more than about 25% of the hydroxyl should remain uncapped since
the hydroxyl increases the water solubility and reduces thickening
efficiency. Of course, if the product contains a relatively high
proportion of hydrophobic residues a greater amount of uncapped
hydroxyl can be tolerated.
[0062] In summary, the complex polymer products are polymeric
compositions prepared by reacting: (a) a polyfunctional reactant
selected from an organic polyol having at least three hydroxy
groups, an organic polyisocyanate having at least three isocyanate
groups, and mixtures thereof; (b) a difunctional reactant selected
from an organic diol, an organic diisocyanate, and mixtures
thereof, the diol being present in the reaction mixture when the
polyisocyanate is present and the diisocyanate being present when
the polyol is present; (c) a monofunctional hydroxyl or amino
compound in an amount sufficient to cap any unreacted isocyanate
remaining from the reaction of reactants a) and b) and to prevent
gelation of the reaction mixture; and optionally d) a hydrophobic
organic monoisocyanate to cap hydroxyl groups remaining from the
reaction of reactants a) and b); wherein at least one of the polyol
and diol contains at least one water soluble polyether segment of
at least 1500 molecular weight, wherein the total carbon content of
all hydrophobic groups is at least 20 and the average molecular
weight of the polyurethane product is about 10,000-200,000.
[0063] As a general rule, the foregoing conditions are true for all
of the polymers of Groups A, B and C. That is, the polymers will
provide good thickening if the polyether segments have molecular
weights of at least 1500 (preferably 3000 to 20,000), the polymers
contain, on the average, at least three hydrophobic groups and at
least two water soluble polyether segments linking the hydrophobes,
the sum of the carbon atoms in the hydrophobic groups being at
least 20, preferably at least 30, and the total molecular weight is
about 10,000 to 200,000, preferably 12,000 to 150,000. The optimum
polyether content will depend, of course, on the bulk and
distribution of the hydrophobic groups in the polymer. Whereas a
total polyether molecular weight of 4000 to 5000 may be suitable
when the polymer contains small external and internal hydrophobes,
the polyether content may have to be substantially increased when
heavier and/or more extensively branched hydrophobic groups are to
be built into the polymer, such as long chain fatty polyols or
amines. About 200 carbon atoms in the hydrophobic portion is the
practical upper limit although it will be understood that it is a
relative matter since the proportion of polyether may be increased
to offset increased hydrophobicity. However, as total molecular
weight increases the viscosity increases and ease of handling
decreases, and therefore the economic usefulness of the products is
substantially diminished.
[0064] The stabilized polyurethane thickener compositions of the
present invention are prepared by combining one or more
polyurethane thickeners, water and a stabilizer including one or
more of diethyl hydroxyl amine or
4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl, wherein the
compositions are substantially free of organic solvent. Typically,
the stabilizer is added to the polyurethane thickener composition
after the preparation of such thickener. However, other methods of
combining the components of the compositions of the present
invention are possible.
[0065] Any amount of stabilizer that stabilizes the polyurethane
thickeners against degradation may be used in the compositions of
the present invention. Typically, the amount of stabilizer compound
is in the range of about 1 to about 5000 ppm, based on the total
weight of the composition. Higher amounts of stabilizer compound
may also be used advantageously, but at increased cost. It is
preferred that the stabilizer compound is present in an amount in
the range of about 10 to about 500 ppm, and more preferably about
50 to about 250 ppm.
[0066] It will be appreciated by those skilled in the art that the
stabilizers of the present invention may be advantageously combined
with other compounds that stabilize poly(ethylene oxide) compounds
against degradation, such as phenothiazine, BHT and BHA. Such known
stabilizers are typically used in an amount in the range of about
0.01 to 0.5 percent by weight.
[0067] One advantage of the stabilizers of the present invention is
that To they are effective in stabilizing polyurethane thickeners
against degradation in very low amounts. In particular, the amount
of the stabilizers of the present invention necessary to stabilize
a polyurethane thickener is typically less than the amount of known
stabilizer needed. A second advantage of the stabilizers of the
present invention is that when such stabilizers are used in
combination with known stabilizers, the amount of known stabilizer
may be substantially reduced. A third advantage of the polyurethane
thickener compositions of the present invention is that they are
resistant to degradation at elevated temperatures, such as
50.degree. C., and preferably 75.degree. C., for an extended period
of time. Such compositions of the present invention may be stable
against degradation for up to 21 days, even at 75.degree. C.
[0068] The water grade polyurethane thickener compositions of the
present invention are substantially free of organic solvent,
preferably essentially free of organic solvent, and more preferably
free of organic solvent. It will be appreciated that small amounts
of organic solvent, such as about 1 percent or less by weight based
on the total weight of the composition, preferably about 0.5
percent or less, and more preferably about 0.25 percent or less,
may be present in the compositions. Such small amounts of organic
solvent may be present due to the presence of other additives in
the composition.
[0069] The stabilizers of the present invention may also be used
advantageously to stabilize solvent grade polyurethane thickeners.
Such solvent grade thickeners typically contain one or more
polyurethane thickening agents, water and organic solvent. Such
organic solvents are typically present in an amount of about 10
percent by weight or greater, based on the total weight of the
composition. Any water miscible organic solvent is suitable for use
in solvent grade polyurethane thickeners. Suitable organic solvents
include, but are not limited to, alkyl carbitols, glycols and the
like. The amount of stabilizers useful in the solvent grade
thickener compositions is the same amount useful in the water grade
thickeners.
[0070] The water grade thickener compositions of the present
invention may contain additional components, such as
compatibilizers, preservatives and the like. It is preferred that
the thickener compositions include one or more of compatibilizers
and preservatives.
[0071] Particularly suitable preservatives for the water grade
polyurethane thickeners of the present invention are the
3-isothiazolone microbicides. Suitable 3-isothiazolone microbicides
include, but are not limited to: 5-chloro-2-methyl-3-isothiazolone,
2-methyl-3-isothiazolone, 2-n-octyl-2-isothiazolone, 4,
5-dichloro-2-n-octyl-3-isothiazolone, benzisothiazolone,
2-methyl-4, 5-trimethylene-3-isothiazolone, and mixtures thereof.
One suitable mixture is 5-chloro-2-methyl-3-isothiazolo- ne and
2-methyl-3-isothiazolone, and in particular a 3:1 ratio of
5-chloro-2-methyl-3-isothiazolone and 2-methyl-3-isothiazolone.
Such 3-isothiazolones are generally commercially available, such as
from the Rohm and Haas Company (Philadelphia, Pa.).
[0072] When used to preserve water grade polyurethane thickeners,
it is preferred that the 3-isothiazolones are water-soluble, such
as 5-chloro-2-methyl-3-isothiazolone and 2-methyl-3-isothiazolone,
or if water-insoluble, such as 2-n-octyl-2-isothiazolone and
4,5-dichloro-2-n-octyl-3-isothiazolone, that they are formulated so
as to be compatible with an aqueous system. Suitable formulations
for the water-insoluble 3-isothiazolones are as emulsions or
microemulsions, such as those disclosed in U.S. Pat. No. 5,444,078
(Yu et al.), herein incorporated by reference to the extent this
patent teaches the preparation of such formulations.
[0073] Any amount of 3-isothiazolone microbicide that preserves the
polyurethane thickener against microbial contamination is suitable
for use in the present invention. Such 3-isothiazolones are
typically used in an amount in the range of about 1 to 1500 ppm,
preferably about 15 to about 500 ppm, and more preferably about 25
to about 125 ppm. The specific amount of 3-isothiazolone used will
depend upon the particular 3-isothiazolone used as well as the
other components in the composition, and such amount would be clear
to one skilled in the art.
[0074] It will be appreciated by those skilled in the art that more
than one preservative may be added to the compositions of the
present invention. Thus, 3-isothiazolones may be effectively
combined with another preservative. Both preservatives may be
combined with the polyurethanes of the present invention.
[0075] The stabilized polyurethane thickener compositions of the
present invention further including a preservative may be prepared
by combining the polyurethane, water, stabilizer and preservative
in any order. It is preferred that both the preservative and
stabilizer be added to the polyurethane. The preservative may be
added to the polyurethane prior to, simultaneously with, or after
the addition of the stabilizer. In one embodiment, the stabilizer
and preservative may be first combined together and then added to
the polyurethane.
[0076] The polyurethane thickener compositions of the present
invention are useful wherever a water based thickener is useful. In
particular, the polyurethane compositions of the present invention
are useful in emulsions, dispersions, and the like, and even more
particularly in latex formulations, such as paint. For example, the
polyurethane thickeners of the present invention may be added to
polymer latex systems at any time during the preparation of such
systems, including during or after polymerization or
copolymerization and by single or multiple additions. Typically,
from about 0.1 to about 10 percent, and preferably 1 to 3 percent,
by weight of the polymeric thickener on polymer latex solids is
adequate to provide suitable levels of thickening and other
properties. However, the exact amount may be higher or lower
depending on the particular system, other additives present and the
like.
[0077] In another aspect, 3-isothiazolone microbicides may be
effectively stabilized with one or more compounds including diethyl
hydroxyl amine or 4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl.
Suitable 3-isothiazolone compounds are those described above.
[0078] Such stabilized 3-isothiazolone compositions typically
include 0.5 to 35 percent by weight, based on the weight of the
composition, of 3-isothiazolone; 0.01 to 20 percent by weight,
based on the weight of the composition, of one or more compounds
including diethyl hydroxyl amine or
4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl; and solvent. It is
preferred that the amount of 3-isothiazolone is in the range of 5
to 15 percent by weight, based on the weight of the composition. It
is preferred that the amount of diethyl hydroxyl amine or
4-hydroxy-2,2-6,6-tetramethylpiperidi- noxyl is in the range of
0.05 to 10 percent by weight, based on the weight of the
composition, and more preferably 0.1 to 5 percent by weight.
[0079] Suitable solvents for the 3-isothiazolone compositions
include one or more of, but are not limited to: water, alcohols,
such as methanol, ethanol, propanol, and the like, esters, such as
ethyl acetate, butyl acetate and the like, aromatic hydrocarbons,
such as benzene, toluene, chlorobenzene, xylenes, and the like,
carbonates, such as propylene carbonate, and glycols, such as
ethylene glycol, diethylene glycol, polyethylene glycol, propylene
glycol, dipropylene glycol, polypropylene glycol, and the like. It
is preferred that the solvent is water or a mixture of water and
glycol.
[0080] It will be appreciated by those skilled in the art that the
stabilizers of the present invention may be advantageously combined
with other known 3-isothiazolone stabilizers. Suitable known
stabilizers for combination with the stabilizers of the present
invention include, but are not limited to: iodic acid, periodic
acid, iodate salts, such as sodium iodate, potassium iodate,
lithium iodate and ammonium iodate, periodate salts, such as sodium
periodate, potassium periodate, lithium periodate and ammonium
periodate, and bromate salts, such as sodium bromate, potassium
bromate, lithium bromate and ammonium bromate. It is preferred that
the stabilizers of the present invention are combined with one or
more other stabilizers, and more preferably combined with one or
more of iodate salts, periodate salts and bromate salts.
[0081] Any amount of known 3-isothiazolone stabilizer may be
combined with the stabilizers of the present invention. Typically,
the ratio of 3-isothiazolone stabilizers of the present invention
to known 3-isothiazolone stabilizers is in the range of 99:1 to
1:99, preferably 25:75 to 1:99, and more preferably 50:50 to
5:95.
[0082] The 3-isothiazolone compositions of the present invention
may optionally contain one or more additives. Suitable additives
include, but are not limited to: surfactants, thixotropic agents,
anti-freeze agents, diluents, and the like. The amount of such
optional additives depends upon the particular 3-isothiazolone
composition and its intended use and is well known to those skilled
in the art.
[0083] The stabilized 3-isothiazolone compositions of the present
invention may be used to inhibit the growth of microorganisms by
introducing a micrcobicidally effective amount of the compositions
onto, into or at a locus subject to microbial attack. Suitable loci
include, but are not limited to: cooling towers, air washers,
boilers, mineral slurries, wastewater treatment, ornamental
fountains, reverse osmosis filtration, ultrafiltration, ballast
water, evaporative condensers, heat exchangers, pulp and paper
processing fluids, plastics, emulsions and dispersions, paints,
latexes, coatings, such as varnishes, construction products, such
as mastics, caulks and sealants, adhesives, photographic chemicals,
printing fluids, household products, cosmetics and toiletries,
shampoos, soaps, detergents, industrial sanitizers, floor polishes,
laundry rinse water, metalworking fluids, lubricants, hydraulic
fluids, oil field fluids, fuel, drilling muds, leather products,
textiles, wood, wood products, surfactant preservation,
agricultural product preservation, diagnostic reagent preservation,
pools and spas.
[0084] The stabilizers of the present invention are particularly
useful in stabilizing one or more 3-isothiazolone compounds in a
polyurethane thickener composition. Such polyurethane thickeners
may be either water grade or solvent grade. It is preferred that
the polyurethane thickener is a water grade thickener. An
particular advantage of the stabilizers of the present invention is
that they are very effective at stabilizing both polyurethane
thickening agents and 3-isothiazolone preservatives in water grade
polyurethane thickener compositions.
[0085] The following examples are presented to illustrate further
various aspects of the present invention, but are not intended to
limit the scope of the invention in any aspect.
EXAMPLE 1
[0086] To each of twelve (four sets of three) commercially
available water grade Polyurethane Thickener A samples containing
water, polyurethane and 25 ppm of a 3:1 mixture of
5-chloro-2-methyl-3-isothiazolone and 2-methyl-3-isothiazolone was
added either diethyl hydroxyl amine ("DEHA") or
4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl ("TEMPOL") as
stabilizer. Three samples of the commercially available
Polyurethane Thickener A without the added stabilizers served as
the controls. All the samples were stored at either 25.degree. C.
or in an oven at either 50.degree. C. or 75.degree. C. for 21 days.
The samples were then removed from the oven and analyzed to
determine any change in viscosity of the samples. The viscosity
measurements were performed on a Brookfield viscometer at shear
rates between 0.1 and 20 reciprocal seconds. The viscosity data are
reported in the percentage of centapoise ("CPS") viscosity
retained. The samples were also analyzed by reverse phase HPLC to
determine the total amount of the 3-isothiazolones remaining. The
results are reported in Tables 1 and 2.
1TABLE 1 3-Isothiazolone Stability in Commercial Polyurethane
Thickener A Temperature DEHA DEHA TEMPOL TEMPOL (.degree. C.)
Control (100 ppm) (200 ppm) (100 ppm) (200 ppm) 25 100 100 100 100
100 50 12 72 65 100 80 75 0 0 21 52 55
[0087] The above data clearly show that both DEHA and TEMPOL are
effective stabilizers for 3-isothiazolones, particularly under the
harsh storage conditions of 75.degree. C.
2TABLE 2 Stability of Polyurethane Thickener A in Percent CPS
Viscosity Retained Temperature DEHA DEHA TEMPOL TEMPOL (.degree.
C.) Control (100 ppm) (200 ppm) (100 ppm) (200 ppm) 25 100 100 100
100 100 50 41 77 94 86 95 75 18 17 85 93 100
[0088] The above data clearly show that both DEHA and TEMPOL are
effective at preventing the degradation of polyurethane thickeners,
even under harsh storage conditions.
EXAMPLE 2
[0089] The procedure of Example 1 was repeated but replacing
commercially available Polyurethane Thickener A with commercially
available Polyurethane Thickener B. Polyurethane Thickener B had a
lower average molecular weight than Polyurethane Thickener A and
contained water, polyurethane and 25 ppm of a 3:1 mixture of
5-chloro-2-methyl-3-isothiazo- lone and 2-methyl-3-isothiazolone.
The results are reported in Tables 3 and 4.
3TABLE 3 3-Isothiazolone Stability in Commercial Polyurethane
Thickener B Temperature DEHA DEHA TEMPOL TEMPOL (.degree. C.)
Control (100 ppm) (200 ppm) (100 ppm) (200 ppm) 25 100 100 100 100
100 50 9 35 35 34 26 75 0 2 29 0 20
[0090] The above data clearly show that both DEHA and TEMPOL are
effective stabilizers for 3-isothiazolones as compared to the
control sample.
4TABLE 4 Stability of Polyurethane Thickener B in Percent CPS
Viscosity Retained Temperature DEHA DEHA TEMPOL TEMPOL (.degree.
C.) Control (100 ppm) (200 ppm) (100 ppm) (200 ppm) 25 100 100 100
100 100 50 72 89 95 94 98 75 24 28 110 17 113
[0091] The above data clearly show that both DEHA and TEMPOL are
effective at preventing the degradation of polyurethane thickeners,
even under harsh storage conditions.
EXAMPLE 3
[0092] The procedure of Example 1 was repeated but replacing
commercially available Polyurethane Thickener A with commercially
available Polyurethane Thickener C. Polyurethane Thickener C had a
higher average molecular weight than Polyurethane Thickener A and
contained water, polyurethane and 25 ppm of a 3:1 mixture of
5-chloro-2-methyl-3-isothiazo- lone and 2-methyl-3-isothiazolone.
The results are reported in Tables 5 and 6.
5TABLE 5 3-Isothiazolone Stability in Commercial Polyurethane
Thickener C Temperature DEHA DEHA TEMPOL TEMPOL (.degree. C.)
Control (100 ppm) (200 ppm) (100 ppm) (200 ppm) 25 100 100 100 100
100 50 16 29 32 57 66 75 0 22 30 45 74
[0093] The above data clearly show that both DEHA and TEMPOL are
effective stabilizers for 3-isothiazolones as compared to the
control sample.
6TABLE 6 Stability of Polyurethane Thickener C in Percent CPS
Viscosity Retained Temperature DEHA DEHA TEMPOL TEMPOL (.degree.
C.) Control (100 ppm) (200 ppm) (100 ppm) (200 ppm) 25 100 100 100
100 100 50 55 96 94 97 100 75 32 76 92 64 94
[0094] The above data clearly show that both DEHA and TEMPOL are
effective at preventing the degradation of polyurethane thickeners,
even at elevated storage temperatures.
EXAMPLE 4
[0095] Three samples of a 3:1 mixture of
5-chloro-2-methyl-3-isothiazolone and 2-methyl-3-isothiazolone were
prepared as follows. Sample A (Control) contained 10% by weight of
the 3-isothiazolone mixture and 90% by weight DI water. Sample B
(Comparative) contained 10% by weight of the 3-isothiazolone
mixture, 4% by weight potassium iodate stabilizer and 86% by weight
DI water. Sample C (Invention) contained 10% by weight of the
3-isothiazolone mixture, 4% by weight potassium iodate stabilizer,
0.1% by weight 4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl and the
remainder as DI water. The samples were then stored in an oven at
400 .degree. C. and analyzed periodically by reverse phase HPLC to
determine the amount of 5-chloro-2-methyl-3-isothiazolone
remaining. The results are reported in Table 7.
7TABLE 7 Percentage of 5-Chloro-2-methyl-3-isothiaz- olone
Remaining Sample A Sample B Sample C Days of Storage (Control)
(Comparative) (Invention) 7 85 100 101 28 66 97 99 42 56 94 99 77
14 83 98 105 23 76 94
[0096] The above data clearly indicate that
4-hydroxy-2,2-6,6-tetramethylp- iperidinoxyl is an effective
stabilizer for 3-isothiazolones.
EXAMPLE 5
[0097] Fifteen samples (D-R) containing DI water and a 3:1 mixture
of 5-chloro-2-methyl-3-isothiazolone and 2-methyl-3-isothiazolone
(the mixture referred to as "ITA") and one or more stabilizers. The
compositions are shown in Table 8. Sample D was the control,
containing no stabilizers. Samples O to R were comparatives, each
containing only a known 3-isothiazolone stabilizer. All samples
were prepared in glass jars and stored in an oven at 55.degree. C.
The samples were periodically removed from the oven and analyzed by
reverse phase HPLC to determine the percentage of
5-chloro-2-methyl-3-isothiazolone remaining. The results are
reported in Table 9.
8TABLE 8 3-Isothiazolone Compositions DI Sample Water ITA TEMPOL
KIO.sub.3 NaIO.sub.3 NaBrO.sub.3 NaClO.sub.3 D* 85.5 14.5 0 0 0 0 0
E 85.4 14.5 0.1 0 0 0 0 F 85.1 14.5 0.4 0 0 0 0 G 81.4 14.5 0.1 4.0
0 0 0 H 81.1 14.5 0.4 4.0 0 0 0 I 81.4 14.5 0.1 0 4.0 0 0 J 81.1
14.5 0.4 0 4.0 0 0 K 81.4 14.5 0.1 0 0 4.0 0 L 81.1 14.5 0.4 0 0
4.0 0 M 81.4 14.5 0.1 0 0 0 4.0 N 81.1 14.5 0.4 0 0 0 4.0 O** 81.5
14.5 0 4.0 0 0 0 P** 81.5 14.5 0 0 4.0 0 0 Q** 81.5 14.5 0 0 0 4.0
R** 81.5 14.5 0 0 0 0 4.0 *Control **Comparative
[0098]
9TABLE 9 Percent of 5-Chloro-2-methyl-3-isothiazolo- ne Remaining
After Storage Sample 8 Days 15 Days 53 Days 60 Days 73 Days D* 0
--** -- -- -- E 0 -- -- -- -- F 0 -- -- -- -- G 97 86 0 -- -- H 102
103 96 1 -- I 100 92 0 -- -- J 103 101 98 91 89 K 99 93 1.4 -- -- L
101 97 0 -- -- M 46 0 -- -- -- N 103 100 0 -- -- O*** 98 85 0 -- --
P*** 98 83 0 -- -- Q*** 99 95 1 -- -- R*** 0 -- -- -- *Control
**Not analyzed ***Comparative
[0099] The above data clearly show that small amounts of
4-hydroxy-2,2-6,6-tetramethylpiperidinoxyl can be used to improve
the effectiveness of known 3-isothiazolone stabilizers, such as
sodium iodate.
* * * * *